1. Technical Field
The present invention relates to a projector.
2. Related Art
There is known a projector that modulates, according to image information, a light beam emitted from a light source and magnifies and projects the light beam on a screen using a projection optical device.
In such a projector, the light beam is tilt-projected upward with the projector fixed in a low position, tilt-projected downward with the projector fixed in a high position, and, besides the projection in the vertical direction, tilt-projected in the horizontal direction. Therefore, there is known a projector including a projection position adjusting device that moves, with respect to an optical system such as an optical modulation device, a projection optical device in a direction orthogonal to a direction in which a light beam is irradiated (a projecting direction) (see, for example JP-A-2006-133419).
The projection position adjusting device disclosed in JP-A-2006-133419 includes a fixed plate, a first moving plate that moves in the vertical direction and the horizontal direction in a plane orthogonal to a projecting direction, a second moving plate that engages with the first moving plate and moves in the horizontal direction together with the first moving plate, an adjusting and moving unit that moves the first moving plate and the second moving plate, and an auxiliary plate that is connected to the fixed plate and holds the first moving plate and the second moving plate between the auxiliary plate itself and the fixed plate. The fixed plate, the first moving plate, the second moving plate, and the auxiliary plate are stacked and arranged in the projecting direction in this order. Plural urging members are disposed between the first moving plate and the second moving plate. The first moving plate is urged to the fixed plate by the urging members to bring the first moving plate into contact with the fixed plate.
With such a configuration, backlash of the first moving plate (backlash of the projection optical device supported by the first moving plate) is prevented. Even when the projection optical device is moved by the projection position adjusting device, shift of a back focus position of the projection optical device is prevented and focus accuracy of a projected image projected from the projector is maintained.
However, the projection position adjusting device disclosed in JP-A-2006-133419 adopts the configuration in which the first moving plate and the second moving plate are supported by using the auxiliary plate in addition to the fixed plate and the first moving plate is brought into contact with the fixed plate by the urging members. Therefore, because a large number of members are used, it is difficult to realize a reduction in size and weight of the projection position adjusting device.